docs(architecture): ADR-013 — family composition, reactive boundary, sweep lease; OQ-11 resolved

- No sibling (alkstore) dependency in-core; reactivity is
  deployment-layer composition above the facade — cadence stays
  embedder-owned (ADR-005), with alkstore the named substrate for it;
  in-crate notify/scheduler/queues/invalidation hooks are non-goals.
- Fleet sweeper lock pinned as 'named exclusive sweep lease'
  semantics; shipped provider unchanged (pg advisory clause);
  provider swaps are ADR-007-shaped substitution doors.
- Composition contract for downstream ADRs: co-tenancy of CAS/GC
  state + reactive machinery + consumer/liveness tables on one fleet
  host; no-cross-store-atomicity ruled; compensation rests on
  idempotent re-puts, windowed deletes, sweeps-as-report-data.
- OQ-11 resolved (the register's one live circular hedge): engine
  features pull their own driver clusters — sqlite becomes feature
  'sqlite' (default-on, carries rusqlite); 'kv'/'large' tier features
  retired; 'local' ungated; pg-pure builds are supported,
  non-default. Deciding fact already in-tree (REQ-2/ADR-009).
- requirements.md: UC-4/REQ-5 records the composition facts
  (operator record 2026-10-11, corroborated by alkstore's
  consumer-inventory).
- Publish guard stated pre-code: facade ships before publish;
  semver-is-contract from first publish (alkstore ADR-017 discipline).
- Amended accepted ADRs' feature wording (ADR-010 §1, ADR-011 §3/§4,
  ADR-003) with supersession notes; README/overview/open-questions/
  backends/store-api/gc aligned; parked index now empty.

Verification: docs-only round (no Rust surface touched); full-tree
single-value check on the feature graph and sweep-lease wording.

docs/architecture/decisions/011-vocabulary-tiers-engines-and-fleet-state.md

@@ -138,6 +138,9 @@ kept (its meaning — this node's own filesystem — stays the
 constructor's meaning even under the shared-media fleet posture,
 where it is explicitly *not* only-node-local; the constructor's
 explicit shared-media assertion, ADR-008 §3, is what disambiguates).
+*(The rename's feature clause is superseded by ADR-013 §4 — engine
+features pull their own driver clusters, tier features retire — the
+tier `large` and constructor wording stands.)*
 
 ### 4. The constructor table (the load-bearing copy of the fleet-validity summary; ADR-010 §3 points here)
 
@@ -149,6 +152,12 @@ explicit shared-media assertion, ADR-008 §3, is what disambiguates).
 | large | local | — (tier default) | yes (tier default-on) | shared media only, explicit assertion |
 | large | pg-lo | `pg-lo` | no | **yes** |
 
+*(The table's engine/constructor columns stand; the Feature column's
+tier-default shape is superseded by ADR-013 §4 — engine features:
+`sqlite` default-on, `postgres`, `mem`, `pg-lo` default-off, `local`
+ungated. Fleet-validity, defaults as constructor presence, and modes
+are unchanged.)*
+
 Constructor modes (dispatch shapes) — pinned here (implied by
 ADR-008 §3's re-routing bullet and the mem tests, but never named):
 - **dual-tier** (the default): kv + large, size-threshold dispatch